Seat sheets of automobiles or trains, and various kinds of sofas and office chairs have a cushion body inside their surface skin materials. As this cushion body, so-called rock wool, which is obtained by entangling stiff fibers such as palms, and hemp or thick synthetic fibers and hardening with rubber or the like, or foamable molded bodies made of various kinds of foamable resin materials are used. These cushion materials have a curved surface composed of concavo-convex shapes satisfying human engineering factors in order to maintain a seating posture which provides no fatigue despite a long-hour seating. If it is intended to effectively manufacture the cushion materials having such a complicated surface shape in large quantities considering its cushion performance, the above-described rock wool that requires a number of manufacturing processes cannot meet the demand. Meanwhile, cushion bodies of foamable resin have been used widely because it can be manufactured by a single process and diversified shapes can be easily obtained. That is, the cushion body of foamable resin is molded into a desired shape at the same time when a foaming is induced by pouring a foamable resin material such as foamable urethane resin into a mold.
Various kinds of fiber cloth or natural or synthetic leather surface skin material are applied to and integrated with the surface of the cushion body formed in this way. For this integration, there is employed a means in which a foamable resin material is poured into a mold with a surface skin material adsorbed along a mold surface so as to integrate a cushion body with a rear surface of the surface skin material at the same time as molding is executed, or a means in which, after the cushion body is formed of a foamable resin material with a mold, the surface skin material is applied to its surface and fixed thereto.
According to the above means of an integral molding, when the surface skin material is set along an inner surface of the mold, it is adsorbed along the inner surface of the mold by means of adsorption means. When the surface skin material is deformed following a surface of a cushion body having a complicated surface configuration, the surface skin material needs to be itself of material having an excellent potential to be stretched. Therefore, since there is a limit to be stretched depending on a material, many wrinkles are likely to occur particularly between a seating surface and a peripheral side surface and up to now, great efforts have been made to remedy this phenomenon.
Further, since this integral molding integrates the cushion body and the surface skin material over their entire surfaces, if a strong force is applied in a direction in which the surface skin material deflects on the surface of the cushion body during actual usage, a shearing force is generated between the surface skin material and the cushion body, the cushion body is often partially torn and then, the surface skin material is separated. The material to be used as the surface skin material is automatically limited in order to exclude an occurrence of such wrinkles, and it is preferable to allow a slight motion between the surface skin material and the cushion body so that any excess force is not applied between them. For the reason, instead of integrating the surface skin material at the same time when the cushion body is molded, a method of applying the surface skin material onto a cushion body molded in advance has been increasingly used.
As described above, as a general method for integrating a molded male surface fastener at the time of molding the cushion body made of a foamable resin material, as illustrated in FIG. 5, an engaging element forming surface of a male surface fastener 1 is placed and fixed on a projecting surface portion 101 on a bottom surface of a mold 100 corresponding to a recess surface of a cushion body so that the engaging element forming surface is opposed to the projecting surface portion and then a foamable resin material is poured in the mold 100 so as to mold the cushion body in a foamed state while the male surface fastener 1 is buried in and integrated with the recess surface of the cushion body with the engaging element forming surface exposed outside. At a time of this foam molding, the foamable resin material needs to be prevented from flowing into a forming region of the male engaging elements. The surface skin material made of various kinds of materials such as pile woven/knit fabric, natural leather, and synthetic leather formed in a shape of a bag corresponding to an outer shape of the cushion body is applied to the cushion body molded by the above-described way. Then, loop-like female engaging elements disposed on a rear surface of the surface skin material are pressed against the engaging element forming surface of the male surface fastener 1 integrated with the cushion body so that the surface skin material is bonded and fixed along the recess surface of the cushion body and prevented from floating from the cushion body.
To prevent the foamable resin material from invading into the engaging element forming region of the male surface fastener when the cushion body is molded, plural technologies are suggested in Japanese Patent Laid-Open Publication No. 2000-516485 (Patent Document 1), U.S. Pat. No. 6,939,596 (Patent Document 2), and Japanese Patent Laid-Open Publication No. 2005-211198 (Patent Document 3).
In Patent Document 1, plural male engaging elements are integrally molded and erected on one surface of a base tape and are coated by a synthetic resin cover to bury the male engaging elements disposed in a peripheral edge of a forming region of the male engaging elements, and an invasion preventing wall made of a foamable resin material is formed to surround the forming region of the male engaging elements. A resin of the same kind as the kind of synthetic resin cover may be filled or not filled into the synthetic resin cover. In order to increase adhesion with a foamable resin mold, particles made of magnetically attractable materials are contained in the resin materials constituting the synthetic resin cover or a magnetic attractable magnet is mixed.
In Patent Document 2, magnetically attractable particles are contained along the outside edge of an engaging element forming region of a molded male surface fastener where plural male engaging elements are integrally molded thereon, and anchor wire where plural fibers are attached to its peripheral surface is directly bonded and fixed to the surface of a flat base member through an adhesive to form a resin invasion preventing wall.
In Patent Document 3, in the male surface fastener, first resin invasion preventing walls that prevent an invasion of a foamable resin material for molding a cushion body extend to the left and right edge portions along a longitudinal direction of a long tape-like base member made of a thermoplastic resin material, plural male engaging elements are provided between the invasion preventing walls at the left and right sides, the male engaging elements are divided for required regions in a longitudinal direction of the base member, and second resin invasion preventing walls that extend in a widthwise direction of the base member are formed between division regions adjacent to each other in the longitudinal direction. The second resin invasion preventing wall extends in the widthwise direction of the surface of the base member, prevents the invasion of the foamable resin material for molding the cushion body to be invaded from the longitudinal direction of the base member, and has hook-like male engaging elements that engage with mating female engaging elements in an upper end portion of the second resin invasion preventing wall.
The second resin invasion preventing wall constitutes a lateral resin invasion preventing wall that continuously extends in a widthwise direction of the surface of the base member, has plural male engaging elements that extend in a forward-to-backward direction from the front and rear wall surfaces in a longitudinal direction of the base member at an upper portion of the lateral resin invasion preventing wall, prevents the lateral resin invasion preventing wall from invading the engaging element forming region made of the molding resin, complements a bonded portion omitted when the male engaging elements having engaging heads having the same shape as the engaging elements formed in the engaging element forming region are bonded to the female engaging elements of the rear surface of the surface skin material, and ensures a required bonding force. The molded male surface fastener that is integrally molded with the cushion body is integrally bonded to the cushion body by the outside region of the first and second invasion preventing walls and the rear surface of the base member. In order to ensure bonding strength between the cushion body and the surface fastener, when the surface fastener is molded, the rear surface is configured as a concavo-convex surface or non-woven cloth is integrated with the rear surface.
According to Patent Document 3, when the cushion body made of the foamable resin material is molded, in order to closely adhere the engaging element forming surface of the molded male surface fastener to the predetermined position of the mold, long magnetic line members are buried and integrated along a longitudinal direction of the base member in each of the portions of the base member of the left and right first resin preventing walls of the molded male surface fastener and the central portion of the base member in the widthwise direction. The magnetic line member is composed of a magnetically attractable line member or a linear magnet. As the magnetically attractable line member, a single metal or a mono-filament made of synthetic resin where particles made of magnetically attractable magnetic materials are mixed is mainly used. However, this line member has excellent flexibility.    Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-516485    Patent Document 2: U.S. Pat. No. 6,939,596    Patent Document 3: Japanese Patent Laid-Open Publication No. 2005-211198